Expansion joints, perhaps?

Perhaps the pipe carries a fluid that changes its pressure or temperature?

Kindly find the attached file and please tell me why the bends are considered@James Garry

Babu,

As I said, these look like expansion bends. If you warm the pipe (by allowing some hot fluid to flow through it) then it will expand. The amount of expansion will depend on the material used to make the pipe.

If the pipe is straight, it may buckle and fail. If it has an expansion loop, the pipe will merely bend (a little).

https://www.engineeringtoolbox.com/steel-pipe-expansion-loop-d_1069.html

James is correct in his answer. If I may add, the recommended method is to bend or produce an omega shape in the pipe, as using right angle bends produces strains on the jointswhen the pipe expands that may themselves lead to failure.

If you want to reproduce the effect experimentally then fun hot water (60C plus) through some of the modern plastic water pipes constrained at both ends. These have a huge coefficient of expansion and the pipe will quickly bow out of shape. Add some 90 degrees joints as per your diagram and observe the results. ;-))

Sorry a couple of typos crept in. 'Run' not 'Fun' some hot water. A space between 'joints' and 'when'

My phone will not allow corrections.

I agreed for hot water but why its also consider for cold water pipe lines. James Garry

2 reasons. Cold water can vary considerably in temperature and pipe fitted at on a day where the air temp is (say) 35C will shrink by as much a 0.4% if the water passing through it is at (say) 4C. The strain induced would easily rupture a joint. Secondly, as James points out, pressure variations need to be allowed for. Valves or taps being turned off suddenly can cause pressure surges. This is the main cause of leaks in national water supplies. In the UK special attention is paid to this when football matches are being televised. There is always a simultaneous rush for the toilet at half-time and the huge number of flushes of the cistern at the same moment causes a huge pressure wave in the pipe system.